AQA Geography A - The Restless Earth

The Restless EarthNature of the earth's crust Distribution of plates The earth's crust is split up into plates. They vary in size Types of plates Oceanic Continental Newer ­ most are less than 200 Older ­ most are over 1500 million million years old. years old Can be renewed and destroyed Cannot be renewed or destroyed Denser Less dense Can sink Cannot sink Plate margins Destructive · Subduction A continental and oceanic plate moving together. The oceanic is forced to sink under the continental as it is denser. As a result of the friction between the plates pressure builds up; it is then released in Earthquakes. Volcanoes are also present at these boundaries because as the oceanic plate is forced down it melts to form magma. The collects to form magma chamber which then rises up through cracks in the continental crust. Pressure increases until an eruption is triggered. As the plates push together, the continental crust is squashed and forced upwards. This causes Fold Mountains. · Collision Two continental plates moving together. Neither can be destroyed so the land is pushed upwards to form Fold Mountains. Earthquakes are common as fiction of the plates rubbing together builds up and is released in the form of an earthquake. Constructive · Two plates moving away from each other. · Mostly found under the sea. · As the plates move apart, magma rises to fill the cracks in the crust. New land is formed.

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Earth quakes occur as the magma erupts to the surface. · Eventually volcanoes are found here due to the build up of new rock · After many eruptions, the volcanoes often erupt out of the sea to form volcanic islands. Conservative · Plates moving side by side. · Because they move at different speeds and angles they often get stuck. · Pressure builds until released in the form of a violent earthquake.…read more

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Farming · Subsidence farming Terraces have been built into the mountainsides. The flat areas retain water and nutrients that would otherwise drain away, making the land more fertile and suitable for farming. · Lamas Provide transport for goods and people Provide meat, wool and milk. Surefooted and strong so suitable for the mountainous environment. Hydro Electric Power · Have exploited the steep slopes, high drops and narrow valleys. · Melting snow adds to the water supply. · Generates cheap electricity for the area.…read more

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Acid lava: Viscous which means it Basic lava: Runny which means it doesn't travel far before cooling. flows long distances before cooling.…read more

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Local economy boosted as a result of tourism; everyone wants to see the `famous' volcano. · Negative Lives lost Ecosystems damaged Housing, farmland and woodland destroyed. The economy has suffered. Responses · Immediate Shelter offered Search and rescue for survivors Ash cleared to allow traffic to flow Distribution of masks · Long term Buildings and bridges rebuilt Replanting forests Roads repaired Efforts to ensure tourism again. Monitoring and predicting volcanic eruptions.…read more

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Super volcanoes Characteristics Mega colossal volcano Erupts at least 1000km3 of material. Have calderas · Depression marking the extent of the collapsed magma chamber. Formation Magma rises at a weak point in the earth's crust: hotspot Magma creates a large bulge in the earth's surface A large mass of rock stops the escape of the magma Cracks appear and gas and ash erupt from the chamber Magma chamber collapses leaving a caldera. Likely effects of an eruption.…read more

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Constructive Friction and pressure from plates moving apart produces less severe earthquakes. Conservative As plates slide past each other they often get stuck. The pressure builds until released in the form of an earthquake.…read more

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Further 6 months to fix all of the roads New rules for buildings to ensure less damage next time Built further apart to stop domino effects Flexible steel frames for high rise buildings Rubber blocks under bridges to act as shock absorbers Differences Effects · More people killed and injured in LEDC than in MEDC Lack of preparation in LEDC in comparison mainly due to lack of funds No training for public resulting in panic No emergency services Had to rely on foreign aid ­…read more

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Computer controlled weights on the roofs of buildings that counteract the shaking of an earthquake. Fire resistant building materials Automatic window shutters to prevent falling glass Steel frame that can sway with the earth movement · How it will help There will be less damage Less to repair Saves money in the long term Preparation · Example Earthquake drills Primary schools every week On one day a year in Japan everyone does a mock earthquake.…read more